To develop small molecular integrin-selective luminescent imaging probes, we have prepared the binary dipicolinate (DPA) Tb III dinuclear macrocyclic complex, Tb 2 (cRGDfK-ODO2A-dimer) (DPA) 2 2or complex I, and reference ligands and Tb III complexes which were purified by HPLC and characterized by NMR, mass spectrometry and luminescence spectroscopy. Luminescence titrations of the structural and bonding model Tb 2 (m-ODO2A-dimer) 2+ complex by DPA 2ion confirmed the molecular formula of the adduct was Tb 2 (m-ODO2A-dimer)(DPA) 2 2-, and the first binary binding con- [a]